Near-Field Polarization Effects in Molecular-Motion-Induced Photochemical Imaging

We demonstrate near-field polarization-sensitive photochemical imaging of the optical near fields produced by metal nanostructures under a variety of illumination conditions. The method relies on the optically induced vectorial molecular mass transport of a light-sensitive polymer. The experimental and theoretical results clearly show that this method can map the three spatial components of the optical near field of complex metal nanostructures. The method was applied to map the electromagnetic near field of silver bowtie nanostructures. In particular, we find that longitudinally polarized plasmons are confined at the top of the metallic structures. Furthermore, the intricate optical near fields in the polymer lead to molecular trapping regions at intensity minima.